Multimeter how to distinguish between fire wire zero wire earth wire
Fire is the phase line, equivalent to the positive level of DC, the industry standard is to use yellow, green and red to represent the ABC three-phase fire; zero line is equivalent to the negative pole of DC, commonly used blue and black on behalf of the word "N". However, there is no positive and negative points of alternating current, the current from the firewire, flow through the power equipment and then through the zero line flows back to the neutral point of the transformer to complete the circuit.
If the line inside the junction box are the same colour, how do we distinguish between zero and fire wire.
Method one, the voltage method, to the socket line as an example
If you determine the ground, the multimeter range gear to the highest voltage gear, to the ground as a common point, respectively, to measure the ground and the other two lines of voltage, no voltage is zero line, there is a voltage of this one is the fire wire.
If we do not know the ground, we must use the leakage switch and light bulbs or other electrical appliances (I only know this method, huh). Measure the voltage method to find the fire wire, connect it to the top of the leakage protector "L" terminal, the other two choose one of the "N" terminal, the load side of the light bulb, and then send power, will trip is the ground, will not trip is the zero line.
Method two, induction method, this method only applies to no ground, there is a ground to be operated in accordance with method one!
The same multimeter to the voltage gear to the highest level, the black pen hanging in the air or wrapped around the finger a few times (so that the value of the display is higher), the red pen to touch the two lines, there is a voltage or voltage is greater than the fire line, no voltage or voltage is smaller than the zero line.
There are also some multimeter has a special measurement of the firewire gear, we just need to adjust the gear to the firewire this gear can be, this gear is generally used to "H" said, the same method of operation and the above.
Multimeter ordinary families do not necessarily have, but the power pen, we should have a pen, now there is an induction pen is very good to use, if the measurement of the firewire it lights red, if the measurement of the zero line it lights green, convenient and easy to use, and here recommended to you. There are like friends can go to the Internet to check.
